Although the asymmetry of species linkage within ecological networks is now well recognized, its effect on communities has scarcely been empirically investigated. Based on theory, we predicted that an asymmetric architecture of antagonistic plant-herbivore networks would emerge at the community level and that this asymmetry would negatively affect community-common plants more than rare ones. We tested this prediction by analyzing the architectural properties of an alpine plant and pre-dispersal seed-predator network and its effect on seed loss rate of plants in the Tibetan Plateau. This network showed an asymmetric architecture, where the common plant species (with a larger aboveground biomass per area) were infested by a higher number of predator species. Moreover, they asymmetrically interacted with specialized herbivores, presumably because of greater seed resource abundance. In turn, the asymmetric interactions led to a higher proportion of seed loss in the common plants at the species level. Our results suggest that asymmetric antagonistic networks may improve species coexistence by contributing to a mechanism of rare-species advantage.

中文翻译：

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种子捕食网络的不对称相互作用有助于稀有物种优势

尽管生态网络内物种联系的不对称性现已得到广泛认可，但其对社区的影响几乎没有经过实证研究。基于理论，我们预测拮抗植物-食草动物网络的不对称结构将在群落层面出现，这种不对称性对群落常见植物的负面影响大于稀有植物。我们通过分析高山植物和传播前种子捕食者网络的建筑特性及其对青藏高原植物种子损失率的影响来测试这一预测。该网络显示出不对称的结构，其中常见的植物物种（每个区域具有较大的地上生物量）受到更多捕食者物种的侵扰。此外，它们与专门的食草动物不对称地相互作用，大概是因为更丰富的种子资源。反过来，不对称相互作用导致普通植物在物种水平上的种子损失比例更高。我们的研究结果表明，不对称拮抗网络可能通过促进稀有物种优势机制来改善物种共存。